CHICAGO, IL — When a project consists of 430,000 square feet of refrigerated space, conventional wisdom would suggest a cooling system consisting of a large mechanical room with a refrigerant such as ammonia.

But the new International Produce Market on Chicago’s near West Side is going against convention. Instead of a mechanical room, there are more than 100 rooftop condensing units. Instead of ammonia, the refrigerant of choice is R-22.

The marketplace, which is scheduled to open in August, is the new, improved version of Chicago’s South Water Market. Produce of all types arrives daily on refrigerated trucks or from local farms, and in turn is sold to buyers from supermarkets, restaurants, and other customers in need of fresh fruits and vegetables.


The several dozen tenants of the market are, in effect, produce wholesalers. The fact that they are independent businesspeople, and often in competition with the next-door neighbor, is part of the reason for the individualized rooftop refrigeration.

With a mechanical room, “Vendors would have to share the plant,” noted Mike Hartwig, vice president of Cooling Equipment Service Inc., Chicago, which has been involved in much of the planning. “Customers would have had to monitor each other. Produce markets operate on thin margins. Each person felt more comfortable controlling their own environment.”

He acknowledged another factor. It’s a bit easier to navigate city regulations for conventional roof-top units vs. ammonia systems.

The long, narrow structure is divided into 12,500-square-foot units. Some tenants have more than one unit. About 80% of the refrigerated space is being serviced by Zero Zone condensing units, Bitzer reciprocating compressors, and Krack coolers. (Tenants had a voice in equipment; a minority opted for other brands.)

The Zero Zone/Bitzer/Krack proposal included customization. “More and more customers are accepting custom-made equipment and they are willing to pay for it because they are seeing the benefits,” said Hartwig.

The Zero Zone condensing units were custom made in Ramsey, MN, by a company long known as Systematic Refrigeration before being acquired by Zero Zone of North Prairie, WI, earlier this year. Said Hartwig, “The customer may pay a little bit more. But that is incidental compared to the size of the jobs, and not having to go back after start-up.”

Hartwig is especially enthusiastic about using Bitzer reciprocating compressors, which are manufactured in Germany and distributed in the United States through Bitzer USA (based in the Atlanta, GA area and formerly known as Delta Heat Transfer).

“I went to Germany a few years ago,” said Hartwig, “and watched the way the employees work. The company puts a lot of time and money into their employees. They want things done just right. If a young person isn’t doing it right, an old timer shows them how. Things have to be done in a certain way.”

Mike Hartwig stands beside one of the condensing units prior to it being lifted to the rooftop of the International Produce Market, seen in the background.


On the technical side, Hartwig said he likes the fact that the manufacturer uses a 20% larger stator than comparable compressors made by other companies, and that it has a cross-hedge in the piston.

“When the compressor runs, the oil actually goes down the side walls of the piston. With a hardened chrome ring in it, it actually sounds like a sewing machine when the compressor is running.” He added that the equipment and the design have helped reduce service problems caused by voltage fluctuations.

In all, about 110 Bitzer compressors will be used, ranging from 30 horsepower down to about 3 horsepower.

The decision to go with R-22 is based, Hartwig said, on costs and the anticipation that the refrigerant will be readily available for at least another 15 years. “That’s usually the lifespan of rooftop equipment.” Despite talk about alternatives to R-22 (which is due for phaseout), Hartwig said, “Our company is not so fast to jump and change when what we are using is successful.”

The cooling coils from Krack are industrial rather than commercial. “That was for the durability and reliability,” Hartwig said. “There is three-quarter-inch tubing inside the coil, so you get a lot of primary cooling area. There are four fins per inch on the coil and that throws air up about 130 feet, which is what you need in produce. With this system design, we lower the temperature difference. That is very efficient for produce storage.”

The mechanical equipment is expected to maintain temperatures ranging from 32 to 45 degrees F, with specific temperatures depending on the type of produce in the refrigerated rooms. Control technology (from the Italian company Dixell) is designed to allow the use of a laptop in remote monitoring and adjusting of temperature, defrost, and other functions, as well as datalogging information.


Cooling Equipment was founded in 1933. It does about $6 million a year, has 25 employees and 17 service trucks. Sixty percent of its business is retrofit. The company finds itself becoming increasingly involved in working with manufacturers on projects in Russia, China, and South America, but its primary business is in the Chicago area. The company is unionized, with almost exclusively commercial and industrial jobs.

Work is gained by word of mouth and through successful troubleshooting of existing equipment that the company had not previously been involved with. “We go into a plant and find a machine that has never worked right,” said Hartwig. “We are able to revamp it and the next thing you know, the customer is asking us to do the refrigeration and air conditioning in the entire plant.”

For the International Produce Market, Cooling Equipment is partnering with the installing Chicago contracting company, Dual-Temp of Illinois. Terry Klaus is serving as the job coordinator for Dual-Temp.

Cooling Equipment is doing the startup and will provide ongoing service. Overall construction has been supervised by FCL Builders of Itasca, IL, with Fred Johanns as project manager.

Hartwig acknowledged a few raised eyebrows with the decision to use German-made recips. But he said it was based on quality of the equipment, manufacturer support, and feedback from Cooling Equipment’s own technicians.

“Frankly, we can just install them and walk away. They are engineered to work. If you’ve got a question, the support [out of the Atlanta area] is excellent. And most importantly, our service people seem to like them. When your service guys are telling you to stay with something, there must be something to it.”

Publication date: 07/01/2002